1. Field of the Invention
The invention relates to a blind, more particularly to a cordless roller blind and a winding device thereof.
2. Description of the Related Art
As shown in FIGS. 1 and 2, U.S. Patent Application Publication No. US2012/0061037A1 discloses a conventional cordless roller blind 1, which is adapted to be mounted on a wall 10, and which includes two seats 11, 12 spacedly arranged in a horizontal direction, a winding unit 13 mounted on an inner side of the seat 12, and a blind unit 14 mounted between the seats 11, 12. The blind unit 14 includes a shaft 141, a link head 142 connected co-movably to the shaft 141 and disposed proximate to the winding unit 13, and a blind 143 rolled releasably on the shaft 141. The seat 12 is L-shaped with one segment 121 to be secured to the wall 10, and another segment 122 protruding transversely from the wall 10 and having two posts 123, 124 that extend transversely toward the winding unit 13.
The winding unit 13 includes a cover 131 disposed at an inner side of the segment 122, a winding wheel 132 mounted rotatably on the post 124 and being connected co-rotatably with the link head 142, and a torsion spring 133 connected at two ends respectively to the post 123 and the winding wheel 132. By virtue of the cooperation between the torsion of the torsion spring 133 and the weight of the blind unit 14, the blind 143 is disposed in a balanced state cordlessly. When an external force is exerted to break the balance, such as pulling up or down the blind 143, the unrolled length of the blind 143 may be adjusted.
When the wall 10 on which the conventional cordless roller blind 1 is mounted is a vertical wall, since the direction of arrangement of the winding wheel 132 and the post 123, to which the torsion spring 133 is connected, is transverse to the vertical wall 10, the conventional cordless roller blind 1 will protrude from the vertical wall 10 by a rather large distance. In other words, the cover 131 is designed to have an elongate shape in order to accommodate for the arrangement of the winding wheel 132 and the torsion spring 133; therefore, the long side of the cover 131 will be perpendicular to the vertical wall 10 upon installation, affecting the overall aesthetic appeal. Further, this downside becomes more prominent if a greater torsion spring 133 needs to be employed to balance the weight of a heavier blind 143, which would also impose application restrictions on the conventional cordless roller blind 1.